The present invention is generally directed to toner processes, and more specifically, to chemical processes wherein there is accomplished the aggregation and fusion or coalescence of latex, colorants, preferably pigment particles, and optional additives to provide toner compositions. In embodiments, the present invention is directed to a chemical toner process wherein known toner pulverization and classification methods are avoided, and wherein in embodiments toner compositions with a volume average diameter of from about 1 to about 20, and preferably from about 2 to about 10 microns in volume average diameter, and narrow particle size distribution of, for example, less than 1.35, and more specifically, from about 1.10 to about 1.25, both as measured on the Coulter Counter can be obtained. The resulting toners can be selected for known electrophotographic processes, including digital processes, and particularly color xerographic imaging and printing processes.
In xerographic color systems, small sized toners of preferably from about 2 to about 7 microns are important to the achievement of high image quality. It is also equally important to have a low image pile height to eliminate, or minimize image feel and to avoid, or minimize paper curling after fusing. Paper curling can be particularly pronounced in xerographic color processes in which relatively high toner coverage as a result of the application of three to four color toners are utilized. During fusing, moisture is driven off from the substrate like paper due to high fusing temperatures of from about 150.degree. C. to 200.degree. C. With only one layer of toner, such as in a single black color, or in highlight color xerographic applications, the amount of moisture driven off during fusing can be reabsorbed back by paper and the resulting print remains relatively flat with minimal paper curl. In process color where toner coverage is high, the relatively thick toner plastic covering on paper can inhibit the paper from reabsorbing the moisture, and lead to substantial paper curling. These and other imaging shortfalls and problems are avoided or minimized with the toners and processes of the present invention.
It is preferable to use small toner particle sizes such as from about 2 to about 7 microns, and with higher pigment loading, such as from about 4 to about 15 percent by weight of toner, so that the mass of toner necessary for attaining the required optical density and color gamut can be significantly reduced to eliminate or minimize image feel and paper curl. The use of lower toner mass also ensures the achievement of image uniformity. Toners prepared in accordance with the present invention enable in embodiments these aforementioned advantages and permit the use of low fusing temperatures, such as from about 100.degree. C. to about 170.degree. C., which will also eliminate or minimize the paper curling.